In “Long-Term Evolution” (LTE) cellular networks, wide area macrocell devices are known as eNodeBs and transmit LTE signals over a large geographic areas. Due to range limitations, a number of eNodeBs are deployed such that the edges of coverage overlap so that continuous coverage can be achieved.
User devices, such as cellular telephones, tablets and computers with cellular network adaptors, known as User Entities (UEs) connect to an eNodeB in order to access the cellular network.
In LTE, the UE has three valid states: switched off, idle mode and connected mode. Switched off represents being completely disconnected from the cellular network. In connected mode, the UE is actively engaged in a communication session with another correspondent node via the eNodeB and the LTE network core. In idle mode, the UE is not actively transmitting or receiving, but is connected to an eNodeB and ready to switch to connected mode to enable a communication session, e.g. making a voice call or starting a data session.
In idle mode the UE, rather than the eNodeB, is responsible for selecting an eNodeB for idle mode association. The UE will typically assess the signal strength to each of the available eNodeBs to determine the eNodeB having the strongest signal and associate with that eNodeB. Since the UE is mobile, the selected eNodeB may change as the relative distances and signal strengths between the UE and the eNodeBs changes.
The UEs receive rules and thresholds governing the initial connection and the manner in which a UE decides to reselect from the connected eNodeB to a different eNodeB. Each eNodeB is configured to transmit the same set of rules and thresholds to all connected UEs in the service area so that all UEs follow the same criteria but decisions are dependent on the observed variables. Each eNodeB uses System Information Block (SIB) messages to broadcast the rules to its connected active mode and idle mode UEs.
The SIBs are defined in 3GPP TS 36.321 V9.3.0 (R9) and 3GPP TS 36.331 V9.3.0 (R9) and each of the SIBs relates to a different aspect of the LTE network. For example, SIB 1 relates to general information about the available PLMNs, SIB 3 and SIB 5 relate to cell-reselection parameters.
SIB messages are broadcast by an eNodeB and received by any UE which is connected to that eNodeB.
Due to the broadcast nature of the SIBs, the idle mode reselection behavior of all connected UEs will be the same. In certain circumstances, this homogenous behavior can be disadvantageous to the mobile network.
Embodiments of the present disclosure address this homogenous behavior.